by Susan Page, Catalina Camia and Susan Davis, USA TODAY

For President Obama, the repercussions of the court's ruling striking down part of the Defense of Marriage Act (DOMA) will mean review and revisions in hundreds of federal laws. In everything from Social Security checks to Pentagon benefits, homosexual married couples now must be treated the same was as heterosexual couples.

For gay rights advocates, the decision opening the door to resume same-sex marriages in California bolstered determination to expand the right to wed for gay men and lesbians. The Human Rights Campaign set a goal to achieve that in all 50 states within the next five years.

And for opponents of gay marriage, the battle turned to state capitals, where 36 states bar gay marriage by statute or constitutional amendment. "We didn't lose," Brian Brown of the National Organization for Marriage said, noting the high court had declined to recognize a constitutional right to marry. "They punted."

The Supreme Court's decisions were undeniably far-reaching, clearing the way for gay marriages to resume in the nation's largest state and striking down a federal law that barred the government from recognizing same-sex marriages sanctioned by states. But previous landmark court decisions on divisive issues, including racial integration and abortion rights, have prompted decades of legal and political fights over their meaning and implementation, not to mention efforts to reverse them.

"The good side of this ruling is that they have affirmed to states that this is a state issue and states can decide," Sen. Rand Paul, R-Ky., said on Glenn Beck's radio show. He counseled allies: "The battle is going to be lost at the federal level. Concentrate on your state."

"With these two historic rulings, we've taken two giant steps forward toward the American promise of equal justice under law," Chad Griffin, president of the HRC, said in an interview. "We celebrate today, and tomorrow we wake up and fight like hell."

On the steps outside the Supreme Court, he fielded a congratulatory call from Obama, aboard Air Force One en route to Africa, then put the cellular call on speakerphone so everyone could hear. "We're proud of you guys," Obama said.

Attorney General Eric Holder promised that the administration would work "expeditiously" to implement the changes in laws and benefits stemming from the demise of DOMA. "Important, life-changing work remains before us," he said.

In the second case, the challenge to California's Proposition 8 banning gay marriage, the court's narrow ruling - that the supporters of the ban didn't have the standing to bring the case - didn't affect other states.

That leaves an expanse of battlegrounds and at patchwork of laws. While every state in New England now recognizes same-sex marriages, for instance, not a single state in the South does. That reflects regional politics: 64% of those in the Northeast support gay marriage, a survey by the Pew Research Center last month found, compared with 43% in the South.

Overall, by 51%-46%, Americans said they favor allowing gay men and lesbians to wed, the first time a majority has espoused that view in the Pew Research Center poll.

The issue seems unlikely to play much of a role in next year's contests for the House, where the overwhelming majority of seats are safely Democratic or safely Republican. The non-partisan Cook Political Report rates just 90 of 435 as swing seats that might reasonably be won by either party.

However, the relatively subdued reaction Wednesday by House Speaker John Boehner and Majority Leader Eric Cantor was a reminder of the balancing act GOP leaders are playing on divisive social issues such as immigration and gay marriage. They need to satisfy base supporters who strongly oppose same-sex marriage but be mindful that language that seems intolerant harms the national GOP brand and the prospects for regaining the White House.

That is a tightrope that the GOP's 2016 presidential contender also may have to walk.

"A robust national debate over marriage will continue in the public square, and it is my hope that states will define marriage as the union between one man and one woman," Boehner said in a written statement. The House had paid to defend DOMA in court when the Obama administration refused to do so.

One of the most outspoken conservative comments came from Minnesota Rep. Michele Bachmann, a favorite of the Tea Party movement. "Marriage was created by the hand of God," she declared. "No man, not even a Supreme Court, can undo what a holy God has instituted."

In the Senate, the issue could raise complications for some Democratic incumbents defending seats in socially conservative states, among them Louisiana Sen. Mary Landrieu and Arkansas Sen. Mark Pryor. They are two of only three Democratic senators who don't support same-sex marriage.

Another race to watch: North Carolina Sen. Kay Hagan, who has endorsed gay marriage. Her state overwhelmingly passed an amendment banning gay marriage in 2012.

Sen. Dianne Feinstein of California and Rep. Jerrold Nadler of New York, senior Democrats on the House and Senate Judiciary committees, reintroduced a measure to repeal the parts of the Defense of Marriage Act that survived the court's scrutiny. Meanwhile, Rep. Tim Huelskamp, a Kansas Republican, said he would push Congress to adopt a constitutional amendment defining marriage as between a man and a woman.

"This doesn't end it," Huelskamp said, saying the issue had been "ignited."

The court decisions underscore the sea change in American attitudes on a fundamental cultural issue, and in an unprecedentedly short period of time. Consider the turnaround since the Defense of Marriage Act was passed in 1996. That year, just 27% in a USA TODAY/Gallup Poll said same-sex unions should be recognized by law as valid, with the same rights as traditional marriages. Sixty-eight percent said they shouldn't.

In the latest Pew Research Center Poll, not only did a majority back gay marriage but even most opponents called legal recognition for such marriages "inevitable."

Bill Clinton, who signed DOMA, and former secretary of State Hillary Rodham Clinton, a potential 2016 presidential contender, were among those who hailed Wednesday's rulings. "The court recognized that discrimination towards any group holds us all back in our efforts to form a more perfect union," they said in a joint statement. "We applaud the hard work of the advocates who have fought so relentlessly for this day."